In a series of earlier disclosures: WO2009/117522A2, WO2010/042514A1, WO2009/117517, WO2008/124706A2, US2010/0084276A1, and US2012/0288948, each of which is incorporated herein by reference in its entirety, a system is shown where nucleic acid bases are read using the electron tunneling current signals generated as nucleobases pass through a tunnel gap functionalized with adaptor molecules. See also Huang et al.1 This method is referred to as “Recognition Tunneling”.2 
U.S. non-provisional patent application Ser. No. 13/838,727, filed Mar. 15, 2013, is understood to disclose a readout device constructed from a planar sandwich of a Pd electrode, a layer of dielectric and a top Pd electrode, where a nano sized opening (or nanopore) is drilled by means of an electron beam. However, drilling through a sandwich of materials sometimes presents challenges. For example, sometimes such drilling may damaging the Pd electrodes, which could lead to electrical shorting.